Storage device employing replaceable storage medium

ABSTRACT

A compact inexpensive optical disk drive adaptable to high-density optical disks is provided by improving a loading mechanism for an optical disk. A mechanism for loading an optical disk, in or from which information is optically recorded or reproduced, into the body of an optical disk drive is mounted on a chassis. The loading mechanism consists of a spindle motor, a lift plate, and a sheet loader. The spindle motor rotates an optical disk. The spindle motor is placed on the lift plate. The sheet loader moves the lift plate vertically to the chassis so as to attach or detach the spindle motor to or from the optical disk. In the storage device, the tilt of the lift plate relative to the chassis is adjusted at three points on the lift plate. Blade springs for constraining the lift plate to move towards the optical disk are interposed between the chassis and lift plate. The points to which spring forces exerted by the blade springs are applied are located on a surface of the lift plate opposite to the optical disk.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a storage device employing areplaceable storage medium. More particularly, this invention isconcerned with a storage device, having a loading mechanism, such as anoptical disk drive employing a replaceable optical disk cartridge thatlooks like a cartridge and has a magneto-optical disk stowed in thecartridge.

[0003] 2. Description of the Related Art

[0004] In recent years, the processing ability and processing speed ofpersonal computers have improved, and the capacities of operatingsystems and application software packages for programs or data haveexpanded. Under these circumstances, storage devices must be compact andlow-cost. Moreover, there is an increasing demand for a storage deviceoffering a large storage capacity and a high processing speed.

[0005] An optical disk drive has begun to prevail as a storage devicecapable of meeting the demands for a compact design, a low cost, a largestorage capacity, and a high processing speed. An optical disk cartridgehaving an optical disk stowed in a cartridge is available as an opticaldisk employed in such an optical disk drive. Along with the prevalenceof the optical disk drive employing the optical disk cartridge, therearises a demand for resistivity to rough handling, stable performance,improved reliability, and reduction in the cost.

[0006] The stability of an optical disk cartridge loaded on a base of anoptical disk drive after being inserted into the optical disk drive maybe impaired if the cartridge is handled roughly. Mechanisms included inthe optical disk drive are required to work properly when the opticaldisk cartridge is inserted in the optical disk drive. Moreover, themechanisms are required to be inexpensive.

[0007] In the optical disk drive employing the optical disk cartridge,an object lens included in an optical system and an optical disk, thatis a storage medium, must run precisely parallel to each other for thepurpose of attaining a high density of the data stored in an opticaldisk. As a solution, a tilt follow-up mechanism may be included in anoptical pickup included in the optical system.

[0008] The solution of including the tilt follow-up mechanism in theoptical pickup included in the optical system has disadvantages that thenumber of elements constituting the optical pickup increases, and thecost of an optical disk drive increases accordingly, and the number ofcomponents that must be controlled increases. These disadvantages becomean obstacle to realization of an inexpensive optical disk drive.

[0009] Another solution is that a mechanism is included for adjustingthe tilts of an object lens and the optical disk during assembling ofoptical elements constituting an optical system for the purpose ofreadily attaining parallelism between the object lens included in theoptical system and the optical disk. An optical disk drive adopting thesolution has been put into practical use. To realize the tilt adjustingmechanism, an actuator including a tilt adjusting mechanism is generallyadopted for the optical pickup.

[0010] In particular, a typical optical pickup is composed of a carriagemovable in a radial direction of an optical disk and an inching actuatorcapable of inching for tracking or focusing while being mounted on thecarriage. Another type of optical pickup is such that the body of acarriage controls the inching in the radial direction (direction oftracks) on an optical disk and an inching actuator mounted on thecarriage controls focusing.

[0011] However, the type of optical pickup composed of the carriagemovable in the radial direction on an optical disk and the inchingactuator capable of inching for tracking or focusing while being mountedon the carriage has disadvantages. Specifically, the number of opticalelements is so large that part costs and machining costs are high.Therefore, this type of optical pickup is not favorable from theviewpoint of reducing the cost of the optical disk drive.

[0012] The type of optical pickup in which the body of the carriagecontrols inching in the radial direction on an optical disk and theactuator mounted on the carriage controls focusing alone helps reducethe cost of an optical disk drive and allows compact design an opticaldisk drive. However, when the actuator is provided with a tilt adjustingmechanism, a tilt adjustment space is needed. This poses a problem inthat the height of the optical disk drive increases. Furthermore, forconstructing a high-performance optical disk drive, the actuator and amagnetic circuit for generating a driving force for the actuator must betilted. This discourages efforts to design a compact optical disk drive.

SUMMARY OF THE INVENTION

[0013] An object of the present invention is to provide a storage devicesuch as an optical disk drive that is compact and inexpensive and isadaptable to high-density optical disks.

[0014] To provide an inexpensive storage device, a pickup to be adoptedmust be of a type in which the body of a carriage controls inching in aradial direction on an optical disk and an actuator mounted on thecarriage controls focusing alone. For realizing a compact design, it isa must that a tilt adjusting mechanism is not included in the opticalpickup. Accordingly, another object of the present invention is toprovide a spindle motor assembly having a tilt adjusting mechanism,making it possible to compactly design a storage device, and enablinguse of an inexpensive optical pickup.

[0015] To accomplish the above objects, the present invention presentsthe first to fifth aspects described below.

[0016] In the first aspect of the present invention, a storage devicehas a mechanism, which loads a replaceable storage medium into the bodyof the storage device, mounted on a chassis. The loading mechanismconsists of a spindle motor, a lift plate, and a lifting mechanism. Thespindle motor rotates the storage medium. The spindle motor is placed onthe lift plate. The lifting mechanism moves the lift plate vertically tothe chassis so as to attach or detach the spindle motor to or from thestorage medium. In the storage device, a tilt adjusting mechanism foradjusting the tilt of the lift plate relative to the chassis when thelift plate is moved towards the storage medium is realized to involve atleast three points on the lift plate. One of the points involved in thetilt adjusting mechanism is regarded as a reference height. A heightadjusting mechanism for adjusting the height of the lift plate relativeto the chassis adjusts the remaining points. Thus, the tilt of thespindle motor relative to the storage medium can be adjusted.

[0017] According to the first aspect, it is unnecessary to include atilt adjusting mechanism in an optical pickup included in an opticaldisk drive. An inexpensive optical pickup can therefore be adopted.Consequently, the cost of the optical disk drive can be minimized.

[0018] In the present invention, a storage device has a mechanism, whichloads a replaceable storage medium into the body of the storage device,mounted on a chassis. The loading mechanism consists of a spindle motor,a lift plate, and a lifting mechanism. The spindle motor rotates thestorage medium. The spindle motor is placed on the lift plate. Thelifting mechanism moves the lift plate vertically to the chassis so asto attach or detach the spindle motor to or from the storage medium. Inthe storage device, a constraining mechanism for constraining the liftplate movement towards the storage medium is interposed between thechassis and lift plate. Points, at which constraining force exerted bythe constraining mechanism is applied, are located on a surface of thelift plate opposite to the storage medium.

[0019] According to the second aspect, the constraining mechanism isused to move the lift plate towards the storage medium. The spindlemotor can be chucked to the storage medium on a stable basis.

[0020] In the third aspect of the present invention, the storage deviceprovided from the second aspect also has a holding mechanism and afreeing mechanism. When the storage medium is not inserted in the bodyof the storage medium, the holding mechanism holds the lift plate awayfrom the chassis. When the storage medium is inserted into the bodythereof, the freeing mechanism moves the holding mechanism in adirection opposite to a direction of insertion of the storage medium soas to free the lift plate. The freeing mechanism allows the constrainingmechanism to quickly move the lift plate towards the storage medium.

[0021] According to the third aspect, the constraining mechanism is usedto move the lift plate towards the storage medium. Consequently, thespindle motor can be quickly chucked to the storage medium.

[0022] In the fourth aspect of the present invention, the storage deviceprovided from the third aspect also includes an eject button and anejecting mechanism. The eject button is used to instruct the body toeject the storage medium. When the eject button is pressed, after theholding mechanism is moved in a direction opposite to a direction ofejection of the storage medium, the ejecting mechanism ejects thestorage medium out of the body of the storage device.

[0023] According to the fourth aspect, the holding mechanism operatesbefore the ejecting mechanism ejects the storage medium out of the bodyof the storage device. Consequently, the spindle motor chucked to thestorage medium is freed before the storage medium is ejected.

[0024] In the fifth aspect of the present invention, the lift plateincluded in the storage device provided from the fourth aspect has twopairs of pins disposed at laterally symmetrical positions in a directionorthogonal to the direction of insertion of the storage medium. Theholding mechanism includes holding members, grooves, and inclinedplanes. The holding members hold the pins with no storage mediuminserted in the main unit. The grooves receive the pins when the holdingmechanism is moved at the completion of inserting the storage mediuminto the storage device. The inclined planes are engaged with the pinswhen the holding mechanism is moved in the direction opposite to thedirection of ejection of the storage medium, whereby the spindle motoris separated from the storage medium.

[0025] According to the fifth aspect, when the eject button is pressed,the holding mechanism is moved in the direction opposite to thedirection of ejection of the storage medium. At this time, the pinsslide on the inclined planes of the holding mechanism, whereby thespindle motor is separated from the storage medium.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be more clearly understood from thedescription as set forth below with reference to the accompanyingdrawings, wherein:

[0027]FIG. 1 is a perspective drawing showing the appearance of a wholeoptical disk drive in accordance with the present invention seen fromthe top thereof;

[0028]FIG. 2 is an exploded perspective drawing showing the structure ofthe optical disk drive, which is shown in FIG. 1, seen from the topthereof;

[0029]FIG. 3 is an exploded perspective drawing showing the structure ofthe optical disk drive, which is shown in FIG. 1, seen from the bottomthereof;

[0030]FIG. 4 is a perspective drawing showing the optical disk drive,which is shown in FIG. 1, with a front panel removed therefrom;

[0031]FIG. 5 is a perspective drawing showing the optical disk drive,which is shown in FIG. 4, seen from the bottom thereof;

[0032]FIG. 6 is a perspective drawing showing the optical disk drive,which is shown in FIG. 4, with a top cover and bottom cover removedtherefrom;

[0033]FIG. 7 is a perspective drawing showing the optical disk drive,which is shown in FIG. 6, with a printed-circuit board removedtherefrom;

[0034]FIG. 8 is a plan view of the optical disk drive shown in FIG. 7;

[0035]FIG. 9 is a perspective drawing showing a main body shown in FIG.7 with a cartridge holder assembly and a shield for a printed-circuitboard removed therefrom;

[0036]FIG. 10 is a perspective drawing showing the structure of achassis of the main body of the optical disk drive in accordance withthe present invention seen from the top thereof;

[0037]FIG. 11 is a perspective drawing showing the structure of thechassis of the main body of the optical disk drive in accordance withthe present invention seen from the bottom thereof;

[0038]FIG. 12 is a perspective drawing showing the chassis shown in FIG.11 with major components including a stationary optical unit, a movableoptical unit, and a spindle motor assembly mounted thereon;

[0039]FIG. 13A is an exploded perspective view showing mounting of thespindle motor assembly in the main body shown in FIG. 12;

[0040]FIG. 13B and FIG. 13C are a side view and plan view of a bladespring for constraining the spindle motor assembly to move;

[0041]FIG. 13D and FIG. 13E are a side view and plan view of anotherblade spring for constraining the spindle motor assembly to move;

[0042]FIG. 14 is a perspective drawing showing the optical disk drive,which is seen from the bottom thereof, with the front panel, cartridgeholder assembly, and printed-circuit board mounted in the main bodythereof shown in FIG. 12;

[0043]FIG. 15 is a perspective drawing showing the optical disk driveshown in FIG. 14 with twisted coil springs substituted for the bladesprings;

[0044]FIG. 16A is a perspective drawing showing the structure of thespindle motor assembly employed in the optical disk drive in accordancewith the present invention;

[0045]FIG. 16B is a perspective drawing showing the spindle motorassembly, which is shown in FIG. 16A, seen from below;

[0046]FIG. 17A is a side view for explaining a conventional way ofrouting a lead extended from a spindle motor included in a spindle motorassembly;

[0047]FIG. 17B is a side view for explaining an example of routing alead extended from a spindle motor included in a spindle motor assemblyaccording to the present invention;

[0048]FIG. 17C is a side view for explaining another example of routinga lead extended from a spindle motor included in a spindle motorassembly according to the present invention;

[0049]FIG. 18A is a side view showing an example of a sheet loaderemployed in an optical disk drive in accordance with the presentinvention;

[0050]FIG. 18B is a plan view of the sheet loader shown in FIG. 18A;

[0051]FIG. 19A is a side view of an example of a sheet loader employedin a conventional optical disk drive;

[0052]FIG. 19B is a plan view of the sheet loader shown in FIG. 19A;

[0053]FIG. 20A is a perspective drawing showing the spindle motorassembly in accordance with the present invention, which is shown inFIG. 16A and FIG. 16B, joined with the sheet loader in accordance withthe present invention shown in FIG. 18A and FIG. 18B;

[0054]FIG. 20B is a perspective drawing showing the spindle motorassembly and sheet loader, which are joined as shown in FIG. 20A, seenfrom the bottom of the sheet loader;

[0055]FIG. 21 is a bottom view of the stationary optical unit and thespindle motor assembly and sheet loader shown in FIG. 20A and FIG. 20Bmounted on the chassis;

[0056]FIG. 22 is a plan view of the optical disk drive shown in FIG. 9with an optical disk cartridge about to be inserted into the opticaldisk drive, showing the states of an ejection arm and a timing arm andthe position of the sheet loader;

[0057]FIG. 23 is a plan view of the optical disk drive shown in FIG. 22with the optical disk cartridge inserted halfway;

[0058]FIG. 24 is a plan view of the optical disk drive shown in FIG. 22with the optical disk cartridge fully inserted thereinto, showing thestates of the ejection arm and timing arm and the position of the sheetloader;

[0059]FIG. 25A to FIG. 25C are explanatory diagrams showing the statesof the sheet loader and spindle motor assembly which are engaged witheach other when the optical disk cartridge is inserted into the opticaldisk drive as shown in FIG. 22 to FIG. 24;

[0060]FIG. 25D is an explanatory diagram showing the states of the sheetloader and spindle motor assembly which are engaged with each other whenthe optical disk cartridge is ejected from the optical disk drive;

[0061]FIG. 26 is a plan view of part of a chassis of a conventionaloptical disk drive showing disposition of a stationary optical unit;

[0062]FIG. 27 is a plan view of part of the chassis of the optical diskdrive for explaining the disadvantage of the disposition of thestationary optical unit in the conventional optical disk drive;

[0063]FIG. 28A is a plan view of part of the chassis showing dispositionof the stationary optical unit in the optical disk drive in accordancewith the present invention;

[0064]FIG. 28B shows a disposition of the same beam splitter as thatshown in FIG. 28A in the stationary optical unit included in theconventional optical disk drive;

[0065]FIG. 28C shows a disposition of the beam splitter included in thestationary optical unit in the optical disk drive in accordance with thepresent invention;

[0066]FIG. 28D shows another example of the beam splitter included inthe stationary optical unit in the optical disk drive in accordance withthe present invention;

[0067]FIG. 29 is an exploded perspective drawing for explainingincorporation of optical elements into the stationary optical unitmounted on the chassis of the optical disk drive in accordance with thepresent invention;

[0068]FIG. 30A and FIG. 30B are perspective drawings showing part of thestationary optical unit in the conventional optical disk drive, thusexplaining how to align a servo unit;

[0069]FIG. 31A and FIG. 31B are perspective drawings showing part of thestationary optical unit in the optical disk drive in accordance with thepresent invention, thus explaining how to align a servo unit;

[0070]FIG. 32A shows the structure of a sensor mount employed in theconventional optical disk drive and the structure of a sensor-mountedflexible printed-circuit board to be mounted in the sensor mount;

[0071]FIG. 32B is a side view showing part of the structure of thesensor mount employed in the conventional optical disk drive, and thusexplaining the disadvantage of the structure;

[0072]FIG. 33A shows the structure of a sensor mount employed in theoptical disk drive in accordance with the present invention, and thestructure of a sensor-mounted flexible printed-circuit board to bemounted in the sensor mount; and

[0073]FIG. 33B is a side view showing part of the structure of thesensor mount employed in the optical disk drive in accordance with thepresent invention, and thus explaining the advantage of the structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Embodiments of a storage device in accordance with the presentinvention will be described in conjunction with the drawings by takingan optical disk drive that is an exemplary embodiment for instance.

[0075]FIG. 1 is a top view of a whole optical disk drive 1 in accordancewith an embodiment of the present invention. An insertion port 1A for anoptical disk cartridge and a front panel 1F having an eject button 1E,which is used to eject an optical disk cartridge from the disk drive,are formed on the front side of the optical disk drive 1. In the presentembodiment, the optical disk drive 1 has a top cover 2 and a bottomcover 6.

[0076]FIG. 2 is a top view showing disassembled components of theoptical disk drive 1 shown in FIG. 1. FIG. 3 is a bottom view showingthe disassembled components of the optical disk drive 1 shown in FIG. 1.In the present embodiment, a printed-circuit board 3, a cartridge holderassembly 4, and a main body 5 are interposed between the top cover 2 andbottom cover 6 and arranged in that order beneath the top cover 2. Thefront panel 1F having the insertion port 1A and Eject button 1E isattached to the main body 5. FIG. 2 and FIG. 3 show the overallstructure of the optical disk drive in accordance with the presentinvention. Individual components required for the present invention willbe described later.

[0077]FIG. 4 shows the optical disk drive 1 shown in FIG. 1 with thefront panel 1F removed therefrom. Part of the main body 5 interposedbetween the top cover 2 and bottom cover 6 is seen to lie behind thefront panel IF. FIG. 5 shows the optical disk drive 1 shown in FIG. 4 asseen from the bottom thereof.

[0078]FIG. 6 shows the optical disk drive 1 shown in FIG. 4 with the topcover 2 and bottom cover 6 removed therefrom. As apparent from thedrawing, the cartridge holder assembly 4 is placed on the main body 5 ofthe optical disk drive 1, and the printed-circuit board 3 is placed onthe cartridge holder assembly 4.

[0079]FIG. 7 shows the optical disk drive 1 shown in FIG. 6 with theprinted-circuit board 3 removed therefrom. FIG. 8 is a plan view of theoptical disk drive 1 shown in FIG. 7. As seen from these drawings, thecartridge holder assembly 4 placed on the main body 5 has a cartridgeholder 40 covering the top of a portion of the main body 5 in which anoptical disk cartridge is inserted. The cartridge holder 40 hascartridge pressers 41, a first shutter opening/closing piece 43, asecond shutter opening/closing piece 45, a guide groove 42, a torsionspring 44, and a bias magnet assembly 46. The cartridge pressers 41press the optical disk cartridge, which is inserted into the main body5, from above. The first and second shutter opening/closing pieces 43and 45 are used to open the shutter of an optical disk cartridgeinserted in the main body 5. The torsion spring 44 is laid between thefirst and second shutter opening/closing pieces 43 and 45. The biasmagnet assembly 46 generates a magnetic field necessary to write data ina disk encapsulated in an optical disk cartridge. A member indicatedwith a dashed line near the second shutter opening/closing piece 45 inFIG. 8 is an ejection arm 11 to be described later.

[0080] A printed-circuit board 30 having a connector 31 formed thereonis located on the main body 5 adjacent to the cartridge holder assembly4. The printed-circuit board 30 is covered with a metallic shield 32.The connector 31 of the printed-circuit board 30 is mated with aconnector (not shown) formed on the printed-circuit board 3 described inconjunction with FIG. 6 when the printed-circuit board 3 is placed onthe main body 5.

[0081]FIG. 9 shows the main body 5 shown in FIG. 7 with the cartridgeholder assembly 4 and the shield 32 for the printed-circuit board 30removed therefrom. A base 51 of a chassis 50 of the main body 5 hassidewalls 54 formed on both edges in the longitudinal direction of themain body. A partition wall 59 linking the sidewalls 54 is formedorthogonally to the sidewalls 54. The partition wall 59 is located at afarther position than the center of the base 51, that is, at a positionfar away from the side of the main body (on the left-hand side of thedrawing) on which an optical disk cartridge is inserted. One side of themain body is left open. An area on the base 51 surrounded by the twosidewalls 54 and partition wall 59 serves as an optical disk cartridgestowage 60 in which an optical disk cartridge is stowed.

[0082] A turntable 82 attached to the rotation shaft of a spindle motoris bared in the center of the optical disk cartridge stowage 60 whilenot projecting from the face of the base 51. The movable optical unit 7is located behind the turntable 82. When an optical disk cartridge isinserted in the optical disk cartridge stowage 60, the shutter of theoptical disk cartridge is opened. At this time, the turntable 82 isthrust into the optical disk cartridge and chucked to the hub of anoptical disk. The optical disk is then rotated. The movable optical unit7 has a carriage that moves in the radial direction of the optical diskrotated by the turntable 82. Laser light is irradiated to a recordingtrack on the optical disk through an object lens mounted in thecarriage, whereby data is read or written from or in the optical disk.The laser light is propagated from the stationary optical unit to bedescribed later to the movable optical unit. The movable optical unit 7has no direct relation to the constituent features of the presentinvention. The description of the structure and operation of the movableoptical unit 7 will be omitted.

[0083] The ejection arm 11 and timing arm 12 are located at the sides ofthe movable optical unit 7 in the optical disk cartridge stowage 60. Theejection arm 11 pivots, with a rotation shaft as a fulcrum, whereby anoptical disk cartridge stowed in the optical disk cartridge stowage 60is ejected out of the base. When the eject button described inconjunction with FIG. 1 and others is pressed, an ejection motor that isnot shown is rotated. This causes the ejection arm 11 to pivot to move asheet loader. Consequently, the optical disk cartridge is ejected. Thetiming arm 12 also pivots with a rotation shaft as a fulcrum. The timingarm 12 is actuated at the timing of an optical disk cartridge's beingfully stowed in the optical disk cartridge stowage 60. The timing arm 12causes the turntable 82 to be chucked to the hub of an optical disk. Themovement of the timing arm 12 will be described later.

[0084] The printed-circuit board 30 having the connector 31 formedthereon and a control IC and others, which are not shown, mountedthereon is placed in a narrower area on the base 51 defined by thepartition wall 59. The stationary optical unit is placed on the surfaceof the chassis 50 opposite to the printed-circuit board 30. Theprinted-circuit board 30 is connected to a sensor, which will bedescribed later, included in the stationary optical unit over a flexibleprinted-circuit board (FPC).

[0085] The structure of the chassis 50 having all components removedtherefrom will be described in conjunction with FIG. 10 and FIG. 11.FIG. 10 shows the chassis 50 seen from the top cover (the top of thechassis). FIG. 11 shows the chassis 50 seen from the bottom cover (thebottom of the chassis). To begin with, the top of the base 51 of thechassis 50 will be described. The top is, as mentioned above,partitioned into a wide area and a narrow area by the partition wall 59.The wide area serves as the optical disk cartridge stowage 60, while thenarrow area serves as a board-mounting section 55.

[0086] A round hole 52 for the spindle motor is bored substantially inthe center of the optical disk cartridge stowage 60. A hole 53 for themovable optical unit is bored adjacently to the hole 52 between the hole52 and partition wall 59. The turntable 82 of the spindle motor is, asshown in FIG. 9, positioned in the round hole 52 for the spindle motor.The movable optical unit 7 is, as shown in FIG. 9, fitted in the hole 53for the movable optical unit. The printed-circuit board 30 is, as shownin FIG. 9, mounted on the board-mounting section 55.

[0087] Next, the bottom of the base 51 of the chassis 50 will bedescribed. The sidewalls 54 are formed in the longitudinal direction onthe bottom of the chassis 50. The bottom is partitioned into four areasby the partition wall 59. An area adjoining an entrance of an opticaldisk cartridge (on the left-hand side of the drawing) serves as aspindle motor assembly storage 61. A subsequent area serves as a movableoptical unit stowage 62. An area farthest from the entrance for anoptical disk cartridge is partitioned into two subareas. One of thesubareas serves as the stationary optical unit 57, while the othersubarea serves as an ejection motor stowage 58.

[0088] The spindle motor assembly stowage 61 has the hole 52 for thespindle motor and posts 56 used to lift or lower the spindle motorassembly. Attachment blocks having attachment holes 131 and 132 used toattach blade springs 13 to be described later are formed on a side ofthe spindle motor assembly stowage 61 acting as the entrance for anoptical disk cartridge. The hole 53 for the movable optical unit andattachment blocks having attachment holes 141 and 142 used to attachblade springs 14, to be described later, are formed in the movableoptical unit stowage 62. The tops of the attachment blocks having theattachment holes 131, 132, 141, and 142 are lower in height than theapical surfaces of the sidewalls 53 and partition wall 59. Thestationary optical unit 57 is die-cast to have dents and blocks formedtherein so that various optical elements can be incorporated in thestationary optical unit 57. The ejection motor stowage 58 accommodatesan ejection motor used to bring the sheet loader 9, which has beendescribed in conjunction with FIG. 9, to an unloaded state.

[0089]FIG. 12 shows the main body 5, as seen from the bottom thereof,having major components mounted on the chassis 50 shown in FIG. 11. Thesheet loader 9 and spindle motor assembly 8 are stowed in the spindlemotor assembly stowage 61 enclosed with the sidewalls 54 and partitionwall 59. The spindle motor assembly 8 has the posts 56 penetratedthrough it. The spindle motor assembly 8 is constrained to move towardsthe base 51 by the first blade springs 13 attached using the attachmentholes 131 and 132 shown in FIG. 11, and the second blade springs 14attached using the attachment holes 141 and 142. The movable opticalunit 7 is placed in the movable optical unit stowage 62 adjoining thespindle motor assembly stowage 61. A plurality of optical elements isintegrated into the stationary optical unit 57, whereby a stationaryoptical assembly 70 is constructed. Furthermore, the ejection motor 68is stowed in the ejection motor stowage 58.

[0090]FIG. 13A shows attachment of the spindle motor assembly 8 to themain body 5 shown in FIG. 12. For attaching the spindle motor assembly8, after the sheet loader 9 is put in the spindle motor assembly stowage61, the posts 56 projecting from the base 51 are penetrated throughguide portions 84 bored in the lift plate 80. At this time, the spindlemotor placed on the face (the lower side of the lift plate 80 in thedrawing) of the lift plate 80 is penetrated through the hole 53.

[0091] The lift plate 80 has its tilt relative to the base 51 adjustedat three points with the spindle motor jutted out of the hole 53. Afirst tilt adjustment screw 16 and a second tilt adjustment screw 17 aredisposed at two out of the three points. The remaining point D on thelift plate 80 serves as a height level. When the posts 56 are penetratedthrough the lift plate 80 and the spindle motor is jutted out of thehole 53, the tip of the first tilt adjustment screw 16 abuts on a screwabutment plane A on the base 51. The tip of the second tilt adjustmentscrew 17 abuts on a screw abutment plane B on the base 51. The heightlevel D on the lift plate 80 abuts on a level C of a referenceprojection projected from the base 51 when the posts 56 are penetratedthrough the lift plate 80.

[0092] When the posts 56 are penetrated through the lift plate 80, thespindle motor assembly 8 is stowed in the spindle motor assembly stowage61 of the chassis 50. At this time, the second blade springs 14 shown inFIG. 13B and FIG. 13C have holes thereof aligned with the attachmentholes 141 and 142 bored in the chassis 50, and are secured by screws 15.The first blade springs 13 shown in FIG. 13D and FIG. 13E have holesthereof aligned with the attachment holes 131 and 132 bored in thechassis 50, and are secured by screws 15. As shown in FIG. 13B and FIG.13D, the first and second blade springs 13 and 14 are bent in order toexert predetermined constraining force. When the proximal ends of thefirst and second blade springs 13 and 14 are fixed to the base 51 usingthe screws 15, the lift plate 80 is constrained to move towards the baseby the distal ends of the blade springs 13 and 14.

[0093] When an optical disk cartridge is fully inserted in a spaceopposite to the spindle motor assembly stowage 61, the spindle motor isjutted out of the hole 53. At this time, a force causing the opticaldisk cartridge to be ejected is exerted by the ejection arm 11 andtiming arm 12. Consequently, a strong force causing the lift plate 80 toseparate from the base 51 works on the entrance-side part of the liftplate 80. In the present embodiment, the constraining force exerted bythe first blade springs 13 is stronger than that exerted by the secondblade springs 14.

[0094] For adjusting the tilt of the lift plate 80 relative to the base51, the tip of the first tilt adjustment screw 16 is abutted on thescrew abutment plane A on the base 51. Moreover, the tip of the secondtilt adjustment screw 17 is abutted on the screw abutment plane B on thebase 51, and the height level B on the lift plate 80 is abutted on thelevel C on the reference projection projected from the base 51. In otherwords, after the height level D on the lift plate 80 is abutted on thelevel C of the reference projection projected from the base 51, thefirst tilt adjustment screw 16 and second tilt adjustment screw 17 areadjusted to abut the screw abutment planes. Thus, the tilt of the liftplate 80 relative to the base 51 is adjusted. After the tilt of the liftplate 80 relative to the base 51 is adjusted, the first tilt adjustmentscrew 16 and second tilt adjustment screw 17 are immobilized.

[0095]FIG. 14 shows the main body 5 shown in FIG. 12 with the frontpanel 1F, cartridge holder assembly, and printed-circuit board 3 mountedthereon after the completion of adjustment of the tilt of the lift plate80 relative to the base 51. As seen from the drawing, the tips of theblade springs 13 and 14 for constraining the spindle motor assembly 8 tomove towards the base are engaged with spring receiving concave parts 85formed in the lift plate 80. This is intended to prevent parts of thelift plate 80, to which constraining force is applied, from beingchanged.

[0096]FIG. 15 shows an example of the main body 5 shown in FIG. 14 inwhich twisted coil springs 18 and 19 are substituted for the bladesprings 13 and 14. The twisted coil springs 18 and 19 are fixed to thechassis 50 using the screws 15. The twisted coil springs 18 and 19 arelocated at positions at which substantially the same constraining forceas that exerted by the blade springs 13 and 14 is exerted by the twistedcoil springs and operated on the lift plate 80. In this example, thetwisted coil spring 18 is formed with two twisted coils that are joined,and constrains the center tongue portion of the lift plate 80 to movetowards the base. The twisted coil springs 19 are two independentsprings. Since a joint of each twisted coil spring 19 and the lift plate80 is almost a pinpoint, the twisted coil springs 19 are shielded withcovers 28 for fear the constraining points on the lift plate may shift.

[0097] Points on the lift plate 80 into which the blade springs 13 and14 or twisted coil springs 18 and 19 are brought into contact may belocated near the joint of the lift plate 80 and chassis 50. The bladesprings 13 and 14 or twisted coil springs 18 and 19 may be brought intocontact with points on the lift plate near the joint of the lift plateand chassis, thus constraining the lift plate to move towards thechassis 50.

[0098] The spindle motor assembly 8 is constrained to move towards thechassis using the blade springs 13 and 14 or twisted coil springs 18 and19. This is because the height of the optical disk drive 1 in accordancewith the present invention is limited. The springs are used to preventthe height of the optical disk drive 1 from increasing. In contrast,when the height of the optical disk drive 1 is large enough, anindependent coil spring could be brought into contact with a point nearthe center of the lift plate 80 coincident with the center of gravity ofthe spindle motor assembly 8. The lift plate 80 could thus beconstrained to move towards the chassis. In this case, the point nearthe center of the lift plate 80 should be coincident with the center ofgravity of the lift plate 80 or a geometrical center of gravity that isthe joint of the lift plate 80 and chassis 50.

[0099]FIG. 16A and FIG. 16B show the structure of the spindle motorassembly 8 employed in the optical disk drive 1 in accordance with thepresent invention. FIG. 16A shows the spindle motor assembly 8 seen fromthe spindle motor-mounted side (face) thereof. FIG. 16B shows thespindle motor assembly 8 seen from the bottom thereof.

[0100] The lift plate 80 that is a major component of the spindle motorassembly 8 has a detection switch 67, two alignment pins 69, the spindlemotor 81, the guide portions 84, the flexible printed-circuit board(FPC) 20, four side pins 83, the first and second adjustment screw holes86 and 87, and slits 88. The detection switch 67 is used to detect theposition of a write protector tab when an optical disk cartridge islanded on the base. When the lift plate 80 is lifted to reach the backof the base, the two alignment pins 69 are jutted to the passage of anoptical disk cartridge on the base 51, and fitted into oblong referenceholes bored in the optical disk cartridge. The spindle motor 81 has theturntable 82 that is chucked to the hub of an optical disk. The guideportions 84 guide the lift plate 80 when the lift plate 80 is lifted orlowered. The four side pins 83 help lift or lower the lift plate 80. Thefirst and second tilt adjustment screws described in conjunction withFIG. 13 are fitted into the first and second adjustment screw holes 86and 87. A coil-coupled portion 21 of the flexible printed-circuit board20 is passed through the slits 88. D denotes the height level.

[0101] The two slits 88 are, as shown in FIG. 16B, bored in the liftplate 80. The coil-coupled portion 21 of the flexible printed-circuitboard 20 is passed through the two slits 88 and returned to the face ofthe lift plate 80 will be described below. The lift plate 80 has thefour spring receiving concave parts 85 formed for accommodating thedistal ends of the blade springs 13 and 14 described in conjunction withFIG. 12 to FIG. 14.

[0102] The reason why the two slits 88 are bored in the lift plate 80 inorder to introduce the coil-coupled portion 21 of the flexibleprinted-circuit board to the back of the lift plate 80 will be describedbelow. As shown in FIG. 17A, a conventional optical disk drive has alarge enough height. There is a clearance S between the lift plate 80and spindle motor 81. The coil-coupled portion 21 of the flexibleprinted-circuit board that is coupled to the winding of a coil includedin the spindle motor 81 can be routed outside through the clearance S.

[0103] However, the height of the optical disk drive in accordance withthe present invention is so small that there is no clearance between thespindle motor 81 and lift plate 80 through which the coil-coupledportion 21 of the flexible printed-circuit board can be routed outside.In this embodiment, therefore, the slits 88 are, as shown in FIG. 17B,bored at positions located inside and outside an area on the lift plate80 occupied by the spindle motor 81. The coil-coupled portion 21 of theflexible printed-circuit board is passed through the two slits 88 andcoupled to the winding of the coil included in the spindle motor 81.FIG. 17C shows another example. A concave part 89 in which part of thecoil-coupled portion 21 of the flexible printed-circuit board is stowedis formed to lie inside and outside the area on the lift plate 80occupied by the spindle motor 81.

[0104] Next, the sheet loader for lifting or lowering the lift plate 80will be described below. FIG. 18A and FIG. 18B show an example of thesheet loader employed in an optical disk drive in accordance with thepresent invention. FIG. 19A and FIG. 19B show an example of a sheetloader employed in a conventional optical disk drive.

[0105] As shown in FIG. 19A and FIG. 19B, a conventional sheet loader 9Ahas an H-shaped body 90A that has an extension 94A. Four predeterminedportions of the body 90A are bent to form lift guides 91A. Each liftguide 91A has a guide groove 92A that receives the side pin 83 describedin conjunction with FIG. 16A and FIG. 16B. The guide groove 92A isdefined with inclined planes 93A that are parallel to each other andmeet the body 90A at an angle of 45°. The side pins attached to the liftplate 80 as described in conjunction with FIG. 16A and FIG. 16B areinserted into the guide grooves. When the sheet loader 9A moves back andforth, the side pins move within the guide grooves 92A along theinclined planes 93A of the lift guides 91A. Consequently, the spindlemotor is lifted or lowered.

[0106] When the tilt of the spindle motor is adjusted to the greatestextent so that an optical disk will not interfere with the inner surfaceof a shell within the shell of an optical disk cartridge, the spindlemotor can be deflected by approximately 30′ at the maximum. According tothe method of loading the spindle motor using the conventional sheetloader shown in FIG. 19A and FIG. 19B, the side pins are lifted alongthe 45°-inclined planes 93A formed on the lift guides 91A of the sheetloader 9A. The sheet loader 9A can be turned a little. However, if thetilt is large, a difference in the height between the left and rightside pins cannot be absorbed to cause a biased contact phenomenon.Consequently, the sheet loader 9A fails to thrust the spindle motorassembly into the back of the base of the chassis.

[0107] In contrast, the sheet loader 9A in accordance with the presentinvention has, as shown in FIG. 18B, an H-shaped body 90 analogous tothat of the conventional sheet loader 9A. The body 90 has an extension94. Four predetermined portions of the body 90 are bent at right anglesto form lift guides 91. Each lift guide 91 consists of a first guide 911and a second guide 912. A guide groove 92 that receives the side pin 83described in conjunction with FIG. 16A and FIG. 16B is formed betweenthe first guide 911 and second guide 912. The side of the first guide911 defining the guide groove 92 is perpendicular to the body 90. Inthis example, the distal end of the side of the first guide 911 definingthe guide groove 92 is shaped like eaves. The side of the second guide912 defining the guide groove 92 is an inclined plane 93 meeting thebody 90 at 45°. The 45°-inclined plane 93 is formed on the side of thesheet loader comparable to the insertion port for an optical diskcartridge.

[0108] The body 90 of the sheet loader 9 has a bracket 98 formed nearthe border between the body 90 and extension 94. A tension spring 96 isattached to the bracket 97. The tension spring 96 is laid between thesheet loader 9 and the chassis 50. Furthermore, the distal portion ofthe extension 94 is formed as an engagement portion that is engaged withthe timing arm as described later. The engagement portion 95 to beengaged with the timing arm is coupled to the ejection motor 68 shown inFIG. 15.

[0109] The side pins 83 formed on the lift plate 80 as described inconjunction with FIG. 16A and FIG. 16B are, as detailed later, locatedon the sides of the second guides 912 parallel to the body 90 with nooptical disk cartridge inserted. While an optical disk cartridge isbeing inserted into the optical disk drive, the sheet loader 9 isimmovable. The side pins 83 stay on the second guides 912. Once theoptical disk cartridge is fully inserted in the optical disk cartridge,the sheet loader 9 is moved quickly and the side pins 83 are put in theguide grooves 92. When the optical disk cartridge is ejected, the sheetloader 9 is moved back to its original position and the side pins 83 areslid on the inclined planes 93.

[0110]FIG. 20A and FIG. 20B show the spindle motor assembly 8 shown inFIG. 16A and FIG. 16B and the sheet loader 9 shown in FIG. 18A and FIG.18B which are joined. FIG. 20A is a top view, while FIG. 20B is a bottomview. The spindle motor assembly 8 and sheet loader 9 have already beendescribed and an iteration will be avoided. FIG. 20A and FIG. 20B show astate in which the side pins 83 are put in the guide groove 92 of thelift guides 91.

[0111]FIG. 21 is a bottom view of the main body 5 in which thestationary optical assembly 70 is incorporated in the stationary opticalunit 57 of the chassis 50, and the spindle motor assembly 8 and sheetloader 9 are joined as shown in FIG. 20A and FIG. 20B. Reference numeral22 denotes a flexible printed-circuit board. As described previously,the side pins 83 are put in the guide grooves 92 with an optical diskcartridge fully inserted, because the lift plate is constrained to movetowards the chassis by the blade springs 13 and 14. Moreover, the sheetloader 9 is constrained to move downwards in the drawing, or in otherwords, towards the insertion port for an optical disk cartridge by meansof the tension spring 96 laid between the sheet loader 9 and chassis 50.

[0112] In the present embodiment, tapping screws may be used as thescrews 15. Moreover, the first and second adjustment screw holes 86 and87 bored in the lift plate 80 and the height level D should preferablybe arranged at intervals of substantially 1200 with the rotation shaftof the spindle motor 81 as a center. In this case, the distances of thefirst and second adjustment screw holes 86 and 87 bored in the liftplate 80 and the height level D from the rotation shaft of the spindlemotor 81 are substantially the same as one another.

[0113] Next, movements made by the spindle motor assembly 8 and sheetloader 9 when an optical disk cartridge is inserted into the opticaldisk drive 1 will be described together with movements made by theejection arm 11 and timing arm 12 in conjunction with FIG. 22 to FIG.25. FIG. 22 shows a state of the optical disk drive 1, which is shown inFIG. 9, into which the optical disk cartridge 10 is about to beinserted. FIG. 23 shows a state of the optical disk drive 1 into whichthe optical disk cartridge 10 is inserted halfway. FIG. 24 shows a stateof the optical disk drive 1 in which the optical disk cartridge 10 isfully inserted. FIG. 25A to FIG. 25C show joined states of the spindlemotor assembly 8 and sheet loader 9 that are attained time-sequentiallywith the progress of insertion of the optical disk cartridge 10 as shownin FIG. 22 to FIG. 24. FIG. 25D shows a joined state of the spindlemotor assembly 8 and sheet loader 9 attained when the optical diskcartridge 10 is ejected.

[0114] Before the optical disk cartridge 10 is inserted into the opticaldisk drive 1, the ejection arm 11 and the L-shaped timing arm 12composed of two arms stand still after pivoting by predetermined anglestowards the insertion port 1A for the optical disk cartridge 10. At thistime, one arm of the timing arm 12 is engaged with the engagementportion 95 of the sheet loader 9 that engages with the timing arm. Thisprevents the sheet loader 9 from moving towards the insertion port 1Afor the optical disk cartridge 10. The timing arm 12 responds to themovement of the optical disk cartridge 10 so as to indicate the timingof chucking the turntable 82 of the spindle motor assembly 8 to the hubof an optical disk.

[0115]FIG. 25A shows the joined state of the spindle motor assembly 8and sheet loader 9 attained at this time. When the optical diskcartridge 10 is not inserted, the side pins 83 fixed to the lift plate80 of the spindle motor assembly 8 are all located on the sides of thesecond guides 912 parallel to the body 90.

[0116] As the optical disk cartridge 10 is inserted into the opticaldisk drive 1, the distal end of the optical disk cartridge 10 is, asshown in FIG. 23, abutted on the ejection arm 11. When the optical diskcartridge 10 is further inserted into the optical disk drive 1, theejection arm 11 pivots. With the insertion of the optical disk cartridge10 into the optical disk drive 1, the shutter of the optical diskcartridge 10 is opened by the first shutter opening/closing piece 43described in conjunction with FIG. 7 and FIG. 8. This mechanism does notfall within the scope of the present invention, and a description of themechanism will be omitted. The joined state of the spindle motorassembly and sheet loader 9 attained at this time is identical to thestate shown in FIG. 25A because the sheet loader 9 does not move.

[0117] When the optical disk cartridge 10 is further inserted into theoptical disk drive 1, the distal end of the optical disk cartridge 10 isabutted on the timing arm 12. This causes the timing arm 12 to pivot.When the optical disk cartridge 10 is fully inserted in the optical diskdrive 1, the timing arm 12 fully pivots. This causes one of the arms ofthe timing arm 12 to disengage from the engagement portion 95 of thesheet loader 9 that engages with the timing arm. Consequently, the sheetloader 9 is moved towards the insertion port 1A for the optical diskcartridge 10 due to tensile force exerted by the tension spring 96described in conjunction with FIG. 21.

[0118]FIG. 25B and FIG. 25C show movements made by the spindle motorassembly 8 and sheet loader 9 at this time. When the optical diskcartridge 10 is fully inserted in the optical disk drive 1, the sheetloader 9 is moved quickly towards the insertion port 1A for the opticaldisk cartridge 10 as indicated with an arrow F in FIG. 25B.Consequently, the side pins 83 located on the sides of the second guides912 parallel to the body 90 are all put in the guide grooves 92. Whenthe movement of the sheet loader 9 towards the insertion port 1A for theoptical disk cartridge 10 is completed, the side pins 82, as shown inFIG. 25C, all land on the bottoms of the guide grooves 92, or in otherwords, on the sheet loader 9. According to the present invention, eachlift guide 91 has only one inclined plane 93. When the sheet loader 9 isused to load the spindle motor assembly, the inclined planes 93 of thelift guides 91 are unused. No pressing force operates in the radialdirection of the spindle motor assembly 8. In the present embodiment,the sides of the first guides 911 of the lift guides 91 defining theguide grooves 92 are formed as vertical contact portions that areperpendicular to the body 90 of the sheet loader 9. When the putting ofthe side pins 83 in the guide grooves 92 is completed, the side pins 83are pressed in the radial direction due to the vertical contactportions. Consequently, pressing force operates on the spindle motor 81in the radial direction of the spindle motor. The pressing force isexerted by the tension spring 96.

[0119] In this state, the turntable 82 of the spindle motor 81 juts outfrom the base 51 into the optical disk cartridge stowage 60 described inconjunction with FIG. 9. The turntable 82 is chucked to the hub of anoptical disk in the optical disk cartridge whose shutter is opened. Withthe turntable chucked to the hub of the optical disk in the optical diskcartridge 10, the tilt of the lift plate 80 relative to the base 51 isheld adjusted owing the first and second tilt adjustment screws 16 and17 and the height level D which are described previously.

[0120] The timing arm 12 responds to the movement of the optical diskcartridge 10 so as to determine the timing of moving the sheet loader 9.Assuming that the length of one of the two arms of the timing 12 fromthe rotation shaft thereof to an end thereof that comes into contactwith the optical disk cartridge 10 is L1 and that the length of theother arm thereof from the rotation shaft thereof to an end thereof thattriggers movement of the sheet loader 9 is L2, the relationship betweenL1 and L2 is L1=L2 or L1>L2.

[0121] When the optical disk cartridge 10 is stowed in the optical diskdrive 1, if the eject button 1E shown in FIG. 15 or the like is pressed,the optical disk cartridge 10 is ejected. At this time, the ejectionmotor 68 is actuated. The ejection motor 68 causes the sheet loader 9 tomove in a direction opposite to the insertion port 1A for an opticaldisk cartridge, or in other words, in a direction of an arrow R in FIG.25D via the engagement portion 95 of the sheet loader that engages withthe timing arm. Consequently, the side pins 83 fixed to the lift plate80 of the spindle motor assembly 8 are moved along the inclined planes93 of the second guides 912. Eventually, the turntable 82 of the spindlemotor 81 chucked to the hub of the optical disk is freed.

[0122] With the movement of the sheet loader 9, the side pins 83 are alldisposed on the sides of the lift guides parallel to the body 90. Thestate shown in FIG. 25A is then restored. When the movement of the sheetloader 9 is completed, the timing arm 12 pivots due to a force exertedby the spring. The arm of the timing arm locks the engagement portion 95of the sheet loader 9 that engages with the timing arm. Consequently,the sheet loader 9 is locked by the timing arm 12. The ejection arm 11starts pivoting when the turntable 82 of the spindle motor 81 chucked tothe hub of the optical disk is freed completely and no longer juts outinto the optical disk cartridge stowage 60. Eventually, the optical diskcartridge is ejected outside the optical disk drive 1.

[0123] As mentioned above, according to the present embodiment, thespindle motor assembly 8 has a tilt adjusting mechanism. This results ina low-cost and compact optical disk drive employing a replaceableoptical disk cartridge.

[0124] Next, the structure of the stationary optical unit included inthe optical disk drive 1 will be described below. Prior to a descriptionof an example of the structure of the stationary optical unit includedin the optical disk drive in accordance with the present invention, thedisadvantages of a conventional optical unit will be described inconjunction with FIG. 26 and FIG. 27.

[0125]FIG. 26 shows the layout of optical elements constituting astationary optical assembly 70A included in a conventional optical diskdrive. In the conventional optical disk drive, a homeward light pathalong which light reflected from an optical disk is routed to a sensormeets an outward light path from a laser light source to the opticaldisk at right angles. A description will be made based on theconventional stationary optical assembly 70A shown in FIG. 26. Laserlight emanating from a laser diode 71 is passed through a collimatorlens 72 and a beam splitter 73 and routed to the movable optical unit 7.The light is then irradiated to an optical disk. This laser light pathfrom the laser diode 71 to the movable optical unit 7 shall be referredto as an outward light path. In contrast, there is a path of lightreflected from the optical disk, passed through the beam splitter 73, aservo unit (wave front dividing element) 74, and a condenser 75, androuted to a sensor 76. This light path along which light split by thebeam splitter 73 is propagated to the sensor 76 shall be referred to asa homeward light path. Reference numeral 77 denotes a light levelmonitor unit. In the conventional optical disk drive, the homeward lightpath is orthogonal to the outward light path.

[0126] In the conventional optical disk drive, another component islocated in an area X in which the sensor 76 is disposed. Interferencewith light by the component occurs in the area X. In the conventionaloptical disk drive, the stationary optical assembly 70A is thereforeseparated from a chassis 50A by a distance Y in order to avoid theinterference by the component occurring in the area X. This poses aproblem in that the overall length (depth) of the optical disk driveincreases.

[0127] In the optical disk drive in accordance with the presentinvention, a homeward light path along which light reflected from anoptical disk is passed through the beam splitter 73 and routed to asensor meets an outward light path, which extends from a laser lightsource to the optical disk, at 90°+α°. A description will be made basedon the stationary optical assembly 70, which is shown in FIG. 28A,employed in the embodiment of the present invention. Laser lightemanating from a laser diode 71 is passed through a collimator lens 72and a beam splitter 73, routed to the movable optical unit 7, andirradiated to an optical disk. This light path is an outward light path.A homeward light path is a path along which light reflected from theoptical disk is separated by the beam splitter 73, passed through aservo unit (wave front dividing element) 74 and a condenser 75, androuted to the sensor 76. An angle at which the homeward light path meetsthe outward light path is larger than 90°. Reference numeral 77 denotesa light level monitor unit for monitoring the amount of light emanatingfrom the laser diode 71.

[0128] In the conventional optical disk drive shown in FIG. 26 and FIG.27, an interface created in the beam splitter 73 meets, as shown in FIG.28B, the outward light path at 45°. In the optical disk drive inaccordance with the present embodiment shown in FIG. 28A, the beamsplitter 73 is, as shown in FIG. 28C, tilted by θ°. This is intended tomake an angle, at which the homeward path of light branched by the beamsplitter 73 meets the outward light path, larger than 90°. Consequently,according to the present embodiment, the homeward light path meets theoutward light path at 90°+2θ°. In this case, the rectilinearity of laserlight propagated along the homeward path remains substantially unvaried.However, light emitted from the beam splitter 73 is deflected by severaltens of micrometers from light incident thereon because of refraction.In the present embodiment, as shown in FIG. 28A, the beam splitter 73 istilted by 6.5° so that the homeward light path will meet the outwardlight path at 90°+13°.

[0129] Since the homeward light path meets the outward light path at90°+2θ°, the position of the sensor 76 is separated from the center ofthe chassis 50. Light will therefore not be interfered with by any othercomponent located near the position of the sensor 76. In the presentembodiment, it is unnecessary to change the position of the sensor 76for the purpose of avoiding interference by any other component.Consequently, the overall length (depth) of the optical disk drive canbe minimized.

[0130] In the present embodiment shown in FIG. 28A, the conventionalbeam splitter 73 is used as it is, and is mounted on the chassis 50while being tilted by a predetermined angle. Alternatively, as shown inFIG. 28D, the beam splitter 73 may not be tilted but a novel beamsplitter 73A having a reflecting surface tilted by 45°+θ° may beemployed. Use of the beam splitter 73A has the same results as those ofthe beam splitter 73.

[0131]FIG. 29 is an explanatory diagram concerning integration ofoptical elements into the stationary optical unit 57 of the chassis 50included in the optical disk drive 1 in accordance with the presentinvention. The stationary optical unit 57 of the chassis 50 isconstructed so that a homeward path of light reflected from the beamsplitter 73 will meet an outward light path at 90°+2θ°. Specifically,the stationary optical unit 57 of the chassis 50 has a first groove 571and a second groove 572 formed therein. The first groove 571 is extendedalong an extension of a direction of movement of a carriage included inthe adjoining movable optical unit 7. The second groove 572 is extendedin a direction that meets the direction of the first groove 571 at90°+2θ°. The beam splitter 73 is located at an intersection between thefirst groove 571 and second groove 572. Moreover, the laser diode 71 andcollimator lens 7 are locked in the first groove 571. The servo unit 74,the condenser 75, and the sensor 76 mounted in a sensor mount 78 arelocked in the second groove 572.

[0132] An alignment projection 74D projects from the servo unit 74. Thealignment projection 74D is fitted into an alignment hole 57C bored inthe second groove 572. Alignment of the servo unit 74 will be describedlater. Moreover, the sensor 76 is mounted on a flexible printed-circuitboard 79. The other end of the flexible printed-circuit board 79 iscoupled to a printed-circuit board to be described later. The lightlevel monitor unit 77 is located at a position opposite to the secondgroove 572 with the beam splitter 73 between them.

[0133] Incidentally, the chassis 50 is generally die-cast. As long as noextra measures are taken, the precision in the dimensions of thestationary optical unit 57 of the die-cast chassis 50 is low. At least acollimator lens-mounted portion 573 of the first groove 571 and acondenser-mounted portion 574 of the second groove 572 are machinedafterwards to have highly precise dimensions. The collimatorlens-mounted portion 573 and condenser-mounted portion 574 each have twoinclined planes that are inclined in mutually opposite directions. Thecollimator lens 72 and condenser 75 are placed on the inclined planes.In the present embodiment, the collimator lens 72 is pressed using asheet presser 72A after placed on the collimator lens-mounted portion573. The collimator lens 72 is thus precisely aligned and locked in thefirst groove 75. Likewise, the condenser 75 is pressed using a sheetpresser 75A after placed on the condenser-mounted portion 574. Thecondenser 75 is thus precisely aligned and locked in the second groove572.

[0134] Now, alignment of the servo unit 74 will be described below.Beforehand, a conventional method of aligning the servo unit 74 will bedescribed below.

[0135]FIG. 30A and FIG. 30B are explanatory diagrams concerning theconventional method of aligning the servo unit 74 in an optical diskdrive. The stationary optical unit 57 has attachment blocks 57A opposedto each other. Each attachment block 57A has, as shown in FIG. 30A, anattachment notch 57B formed in the top thereof. The servo unit 74serving as a wave front dividing element for dividing incident lightinto three light rays is interposed between the opposed surfaces of theattachment blocks 57A. The servo unit 74 has two wedged parts 74A and74B whose longitudinal sections are tapered. A curved plane 74C issandwiched between the wedged parts 74A and 74B. The surfaces of thewedged parts 74A and 74B are inclined in mutually opposite directions. Aflange 74F is formed on both sides of the top of the servo unit 74.

[0136] For placing the servo unit 74 in a space between the attachmentblocks 57A, the flanges 74 are engaged with the attachment notches 57B.The width of the servo unit 74 is smaller than the distance between thetwo opposed attachment blocks 57A. After the flanges 74 are engaged withthe attachment notches 57B, the servo unit 74 is, as shown in FIG. 30B,moved laterally to have its position determined.

[0137] For aligning the servo unit 74, a light source for emittingreference light, a mechanism for aligning the optical disk drive, amechanism for moving the servo unit 74, and an adjustment facilityhaving the ability to monitor light on a screen are installed outsidethe optical disk drive. After the servo unit 74 is placed in the spacebetween the attachment blocks 57A, the adjustment facility emitsreference light to the servo unit 74. The servo unit 74 is then moved sothat the light irradiated to a screen located at a position opposite tothe adjustment facility with the servo unit 74 between them will fall ona proper position on the screen. The position of the servo unit 74 isthus adjusted. The servo unit 74 is then fixed in the position whichpermits the reference light to fall on the proper position, using anadhesive. For attaching the servo unit 74 to the attachment blocks 57Aaccording to the conventional method, the expensive and high-precisionfacility is needed. Besides, many man-hours are required for adjustment.This leads to an increase in the cost of the whole optical disk drive.Moreover, too much time is required for maintenance of the facility andadjustment of the position of the servo unit. This poses a problem inthat the efficiency in manufacturing the optical disk drive is verypoor.

[0138] According to the present invention, as shown in FIG. 31A, thealignment projection 74D is formed on the bottom of the servo unit 7having the same structure as the conventional servo unit. Moreover, thealignment hole 57C that receives the alignment projection 74D is boredin the bottom of the stationary optical unit 57 between the attachmentblocks 57A. The alignment hole 57C is finished highly precisely throughpost-machining. While the alignment projection 74D projecting from thebottom of the servo unit 74 is fitted into the alignment hole 57C boredin the bottom of the stationary optical unit 57, the flanges 74F areengaged with the attachment notches 57B. Consequently, the servo unit 74is, as shown in FIG. 31B, attached to the attachment blocks 57A.

[0139] Consequently, the present invention obviates the necessity of theexpensive high-precision adjustment facility. The work of attaching theservo unit 74 that is an optical element can be simplified and speededup. This leads to a reduction in the cost of an optical disk drive.

[0140] Finally, the structure of a printed-circuit board on which asensor to be locked in the farthest end of the second groove 572 ismounted will be described below. Beforehand, the disadvantage of theconventional structure of a sensor-mounted printed-circuit board will bedescribed.

[0141]FIG. 32A and FIG. 32B are explanatory diagrams concerning theconventional structure of a flexible printed-circuit board, on which thesensor 76 is mounted, adopted for an optical disk drive. The sensor 76is generally mounted on the flexible printed-circuit board 79. Theflexible printed-circuit board 79 is mounted in a sensor mount 78A. Theother end of the flexible printed-circuit board 79 is coupled to theprinted-circuit board 30 shown in FIG. 22 to FIG. 24. The flexibleprinted-circuit board 79 has a board-coupled portion 79A that is coupledto the printed-circuit board and a sensor-mounted portion 79B. Part ofthe sensor-mounted portion communicating with the sensor-mounted portionhas a smaller width. The sensor mount 78A is shaped like a rectangle,and has a concave part 78B, which receives the sensor-mounted portion79B of the flexible printed-circuit board 79, formed in the centerthereof. Attachment holes 78C are bored across the concave part 78B. Oneedge of the concave part 78B facing the bottom cover (lower end in thedrawing) is left open. A leading-out groove 78D used to lead out thesmall-width part of the board-coupled portion 79A of the flexibleprinted-circuit board 79 is formed on the other edge of the sensor mount78A facing the top cover (upper end in the drawing).

[0142] The sensor-mounted portion 79B of the flexible printed-circuitboard 79 is, as shown in FIG. 32B, locked in the concave part 78B of thesensor mount 78A using an adhesive. The board-coupled portion 79A of theflexible printed-circuit board 79 is coupled to the printed-circuitboard 30 using a solder 33. In this case, for preventing the sensor 76in the concave part 78B from moving due to tension exerted by theflexible printed-circuit board 79, the flexible printed-circuit board 79has been folded in the past. This is intended to prevent tension frombeing applied to the sensor-mounted portion 79B. Moreover, a thinexpensive flexible printed-circuit board is adopted as the flexibleprinted-circuit board 79 so that the flexible printed-circuit board 79will exert little tension.

[0143] According to the conventional structure of a sensor-mountedprinted-circuit board, since manual work is necessary to fold theflexible printed-circuit board 79, many man-hours are required.Moreover, the method of folding the flexible printed-circuit board 79 isdifferent from worker to worker. It occurs that the flexibleprinted-circuit board 79 is broken because of insufficient folding, oron the contrary, that the flexible printed-circuit board 79 is cutbecause of excessive folding. Furthermore, the adoption of a thinflexible printed-circuit board as the flexible printed-circuit board 79increases the cost of an optical disk drive.

[0144] Furthermore, the adhesion of the adhesive used to bond thesensor-mounted portion 79B of the flexible printed-circuit board 79 andthe sensor mount 78A deteriorates with a rise in ambient temperature.This causes the distal end 79C of the sensor-mounted portion 79B to movewithin the sensor mount 78A as indicated with a dashed line in FIG. 32Bdespite application of only slight tension. The position of the sensor76 is thus changed to disable accurate detection.

[0145] In contrast, according to the structure of a sensor-mountedprinted-circuit board shown in FIG. 33A and FIG. 33B and adopted in thepresent invention, a sidewall 78G is formed on even an edge of a concavepart 78E of the sensor mount 78 facing the top cover. According to thepresent invention, the concave part 78E is shaped like a rectangle andsurrounded with sidewalls 78G, though a drawn-out groove 78D traversesone sidewall 78G. On the other hand, according to the present invention,a flexible printed-circuit board having the same shape as theconventional one shown in FIG. 32A and FIG. 32B may be adopted as theflexible printed-circuit board 79. The procedure of mounting the sensor76 on the sensor-mounted portion 79B is the same as the conventionalone.

[0146] However, according to the present invention, when the flexibleprinted-circuit board 79 is locked in the concave part 78E using anadhesive, the distal end 79C of the sensor-mounted portion 79B mustimpact against the sidewall 78G. Therefore, even if tension exerted bythe board-coupled portion 79A of the flexible printed-circuit board 79is applied to the sensor-mounted portion 79B, or even if the adhesion ofthe adhesive deteriorates due to a rise in ambient temperature, theflexible printed-circuit board 79 will not move farther. This is becausethe distal end 79C of the flexible printed-circuit board abuts againstthe sidewall 78G. It is therefore unnecessary to fold the flexibleprinted-circuit board 79 in advance. Moreover, an expensive thinflexible printed-circuit board need not be adopted as the flexibleprinted-circuit board 79.

[0147] In the example shown in FIG. 33A and FIG. 33B, the sidewall 78Gis formed even on the edge of the concave part 78E of the sensor mount78 facing the top cover. To prevent the distal end 79C of the flexibleprinted-circuit board 79 from moving due to a rise in temperature, aplurality of projections may be formed on the edge of the concave part78B of the sensor mount 78, which is described in conjunction with FIG.32A and FIG. 32B, instead of the sidewall. The distal end 79C of theflexible printed-circuit board 79 may be abut against the projections.

[0148] As mentioned above, according to the present invention, the shapeof the sensor mount 78 is modified. Consequently, a shift of a flexibleprinted-circuit board derived from tension exerted by the flexibleprinted-circuit board will not occur. This obviates the necessity offolding the flexible printed-circuit board in advance, and leads to animproved ease-of-manufacture. Moreover, since an expensive thin flexibleprinted-circuit board need not be adopted, the manufacturing cost of anoptical disk drive is reduced.

[0149] As mentioned above, the improvement of an optical system inaccordance with the present invention makes it easy to manufacture theoptical disk drive 1. Consequently, the cost of the optical disk drivecan be minimized.

[0150] In the aforesaid embodiment, a storage device in accordance withthe present invention has been described based on an optical disk driveemploying a magneto-optical disk as a storage medium. A loadingmechanism in accordance with the present embodiment described inrelation to the embodiment may be adapted to a storage medium other thanthe magneto-optical disk. For example, the loading mechanism inaccordance with the present invention may be adapted to a compact disk(CD) that is reproducible and reprogrammable, an optical disk such as adigital versatile disk (DVD), and a floppy disk realized with a magneticdisk. In this case, the disk may not be stowed in a cartridge or may bestowed in a carrier or a holder only when inserted into a storagedevice. Moreover, the loading mechanism in accordance with the presentinvention is adaptable to a type of storage device into which a disk isloaded while being placed on a tray.

[0151] Likewise, a stationary optical unit in accordance with thepresent invention described in relation to the aforesaid embodiment maybe adapted to a storage medium other than the magneto-optical disk. Forexample, the stationary optical unit in accordance with the presentinvention can be applied to an optical disk drive employing a compactdisk (CD) that is reproducible or reprogrammable or an optical disk suchas a digital multipurpose disk (DVD).

[0152] Furthermore, a storage device in accordance with the presentinvention includes not only a disk drive for recording or reproducinginformation in or from a storage medium shaped like a disk but also adisk drive capable of creating or formatting a storage medium. Thestorage device in accordance with the present invention also includes astorage device employing a storage medium such as a memory card.

What is claimed is:
 1. A storage device having a mechanism, which loadsa replaceable storage medium into the body of said storage device,mounted on a chassis, said loading mechanism including a spindle motorfor rotating said storage medium, a lift plate on which said spindlemotor is placed, and a lifting mechanism for moving said lift platevertically to said chassis so as to attach or detach said spindle motorto or from said storage medium, said storage device characterized inthat: a tilt adjusting mechanism which adjusts the tilt of said liftplate relative to said chassis when said lift plate is moved towardssaid storage medium is realized to involve at least three points on saidlift plate; one of the three points is regarded as a reference heightlevel; a height adjusting mechanism capable of adjusting the height ofsaid lift plate from said chassis is realized to involve the remainingpoints; and the tilt of said spindle motor relative to said storagemedium can thus be adjusted.
 2. A storage device having a mechanism,which loads a replaceable storage medium into the body of said storagedevice, mounted on a chassis, said loading mechanism including a spindlemotor for rotating said storage medium, a lift plate on which saidspindle motor is placed, and a lifting mechanism for moving said liftplate vertically to said chassis so as to attach or detach said spindlemotor to or from said storage medium, said storage device characterizedin that: a constraining mechanism which constrains said lift plate tomove towards said storage medium is interposed between said chassis andsaid lift plate; and points to which constraining force exerted by saidconstraining mechanism is applied are located on a surface of said liftplate opposite to said storage medium.
 3. A storage device according toclaim 2 , further comprising: a holding mechanism which holds said liftplate away from said chassis with said storage medium not inserted insaid body; a freeing mechanism which frees said lift plate by movingsaid holding mechanism in a direction opposite to a direction ofinsertion of said storage medium at the completion of inserting saidstorage medium into said body, and allowing said constraining mechanismto quickly move said lift plate towards said storage medium.
 4. Astorage device according to claim 3 , further comprising: an Ejectbutton used to instruct said body to eject said storage medium; and anejecting mechanism which, when said Eject button is pressed, ejects saidstorage medium inserted in said body out of said storage device aftermoving said holding mechanism in a direction opposite to a direction ofejection of said storage medium.
 5. A storage device according to claim4 , wherein: two pairs of pins are located at laterally symmetricalpositions on said lift plate in a direction orthogonal to the directionof insertion of said storage medium; and said holding mechanism includesholding members for holding said pins with said storage medium notinserted in said body, grooves into which said pins are put when saidholding mechanism is moved at the completion of inserting said storagemedium into said body, and inclined planes that are engaged with saidpins when said holding mechanism is moved in the direction opposite tothe direction of ejection of said storage medium, and that thus separatesaid spindle motor from said storage medium.
 6. A storage deviceaccording to claim 1 , wherein a constraining mechanism which constrainssaid lift plate to move towards said storage medium is interposedbetween said chassis and said lift plate, and points to whichconstraining force exerted by said constraining mechanism is applied arelocated on a surface of said lift plate opposite to said storage medium.7. A storage device according to claim 1 , wherein said adjustingmechanism consists of screw holes bored in said lift plate and tappingscrews to be fitted into said screw holes.
 8. A storage device accordingto claim 1 , wherein a reference projection that abuts on said heightlevel is formed on said chassis so that the reference projection will beopposed to said height level.
 9. A storage device according to claim 1 ,wherein said adjusting mechanism involves three points that are arrangedat intervals of substantially 120° with the rotation shaft of saidspindle motor as a center.
 10. A storage device according to claim 9 ,wherein said three points involved in said adjusting mechanism areseparated from the rotation shaft of said spindle motor by asubstantially equal distance.
 11. A storage device according to claim 2, wherein said constraining mechanism constrains the center of gravityof said lift plate.
 12. A storage device according to claim 6 , whereinsaid constraining mechanism constrains the geometric center of gravitythat is a joint in said lift plate adjusting mechanism and said chassis.13. A storage device according to claim 6 , wherein said constrainingmechanism constrains respective points near a joint in said lift plateadjusting mechanism and said chassis to move.
 14. A storage deviceaccording to claim 6 , wherein consideration is taken into force imposedon said spindle motor with said storage medium loaded or the moment ofsaid spindle motor, so that when the position of said constrainingmechanism is determined properly, said constraining mechanism will exerta minimum amount of force.
 15. A storage device according to claim 11 ,wherein said constraining mechanism consists of blade springs.
 16. Astorage device according to claim 1 , wherein said constrainingmechanism consists of twisted coil springs.
 17. A storage deviceaccording to claim 1 , wherein slits are located at positions inside andoutside an area on said lift plate occupied by said spindle motor, anextended lead to be coupled to a winding included in said spindle motoris led out to the back of said lift plate through said slit locatedinside the area, and led back to the surface of said lift plate throughsaid slit located outside the area.
 18. A storage device according toclaim 5 , wherein the sides of said grooves, which are included in saidholding mechanism and opposed to said inclined planes, are formed asvertical contact portions, and said contact portions cause a pressingforce oriented in a radial direction to operate on said pins with saidpins received by said grooves.